HomeMy WebLinkAbout05110113 Correspondence
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MOORE
ENGINEERING
MOORE ENGINEERING
SERVICES, INC.
4790 West 73rd Street
Ind~napolis, Ind~na 46268
Phone (317) 291-1052
FAX (317) 298-2729
Jim Ochs
One Civic Square
Cam1el, IN 46032
Providence Shoppes
]2545 Old Meridian
Carmel, IN 46032
Dear, Mr. Ochs
Regarding the dryer vent sizing at the Providence Shoppes project. The
2003 IMC allows for a maximum length of 25ft. of 4 inch round exhaust duct
from the dryer location to the outlet terminal. The maximum lcngth of duct shall
be reduced 5 feet for each 90 degree bend.
I have compiled dryer manufactures data and found the major
manufacturers to bc similar in the CFM requirements.
May tag - 180 CFM
Whirlpool -less than 200 CFM
GE-175 CFM
May tag specifies an allowable static pressure of 0.83 inches of water
column.
Therefore, using 200 CFM and 0.60 inches of water column as
conservative design parameters, 4 inch round exhaust duct would meet these
parameters at 27 feet total developed length. This is consistent with the 25 foot
developed length allowed by code. Using the same design parameters on 5 inch
round exhaust duct would yield a 80 foot developed length available to meet
design.
4" round
Ld ~ .60 in sp
2.2 in spll 00 feet
= 27 feet
5" round
Ld = .60 in sp
.75 in spll 00 feet
=80 feet
In a ,it" visit, I verified the instal1ation and find that the longest developed
length is a combination of] 5 feet of 4 inch round with 2-4 inch 90 degree bends
combined with 30 feet of 5 inch round with 3-5 inch 90 degree bends. Using the
design parameters of 200 CFM exhaust, this installation will yield a static
prcssure of .85 inches of water column.
SP = ] 5ft + 2(5ft) *2.2in H20 + 25ft + 3(5ft) * .75in H20
] 00 feet ] 00 feet
= .55 + .30 = .85in H20
With the city approval, I am requiring that the installation contractor
change the exhaust duct so the maximum installation would have] -4 inch 90
degree bend, ]-4 inch by 5 inch increaser, 40 feet of 5 inch round pipe, and 4-5
"0:7
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A~
MOORE
ENGINEERING
MOORE ENGINEERING
SERVICES, INC.
4790 West 73rd Street
Indianapolis, Indiana 46268
Phone (317) 291-1052
fAX (317) 298-2729
inch 90 degree bends. The static pressure on this installation would be .56 inches
of water column.
sp = 5ft * 2.2in H20 + 40ft + 4(5ft) * . 75in H20
100ft 100ft
.11 + .45 = .56in H20
Given this information, I will certify that the dryer vent installations, with
the proposed changes to 5 inch round in lieu of 4 inch round, are within design
criteria and will perform as intended by the manufacturer.
Please call me at 31 7-291-1052 with any questions.
~
~I
;r
Douglas R. Moore P.E.
Attachments:
May tag installation instructions - page 5
Friction Chart for Air
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W~ ~ 15";)3-06
JO~ ?~7rOb
ELECTRIC AND GAS DRYER
Weather Hood Type
Recommended Use only for short run installation
~ ~ I. CO
4"(10,16 em) 21/2"(6,35 em)
No. 01900 Rigid Metallic Flexible' Rigid Metallic Flexible'
elbows
0 24.4 m (80 ft.) 12.4m (41 ft.) 22.6 m (74 ft.) 10.1 m (33 ft.)
1 20.7 m (68 ft.) 11.2 m (37 It) 18.9 m (62 ft.) 8.8 m (29 It)
2 17.4 m (57 ft.) 10.1 m (33 ft.) 15.5 m (51 ft.) 7.6 m (25 It)
3 14.3m (47 ft.) 9.0 m (29 ft.) 12.5 m (41 ft.) 6.5 m (21 ft.)
. Do not use non metallic flexible duct.
.
Exhaust systems longer than recommended can extend drying times, affect machine operation
and may collect lint.
The exhaust duct should end with an exhaust hood with a swing out damper to prevent back
drafts and entry 01 wildlife. Never use an exhaust hood with a magnetic damper.
.The hood should have at least 12 inches (30.5 ,cm), 0.1 clearance between the bottom of the
hood and the ground or other obstruction. The.h.ood opening should point down.
Never install a screen over the exhaust outlet.
When po"ssible, do not exhaust the drYer'directly'into a window well in order to avoid lint build' .
up. Do not exhaust under a house or por;h. " ..... .. .
II exhaust ductwork must run through an unheated area, the duct should be insulated and slope
slightly down towards the exhaust hood to reduce condensation and lint build-up. '.
Inspect and cleantheinterior or the "exhaust system at least once a year. Disconnect electrical
service prior to cleaning. ' '.'
Frequently check to be sure the exhaust hood damper opens and closes freely.
,""
.
..
.
, .
.
.
.
If new dryer is installed into an existing exhaust system you must be sure:
. The exhaust system meets all local, state and national codes.
. That plastic flexible duct is not used.
. Inspect and clean all lint accumulation lrom the interior 01 the existing duct.
. The duct is not kinked or crushed.
. The exhaust hood damper opens and closes freely.
The static pressure in any exhaust system must not exceed 0.83
inches of water column, or be less than O.
This can be measured with the dryer running with a manometer at the point where
the exhaust duct connects to the dryer. A no heat setting should be used.
The dryer tumbler should be empty and the lint filter clean.
5
280
TRANE AIR CONDITIONING MANUAL
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FRICTION LOSS IN INCHES OF WATER PER 100 FT
(Based on Standard Air of 0.075 Ib per ClI ft density flowing through average, cleon, round, galvanized
metal ducts having appro)(;molely 40 ioints per 100 ft.)
FIGURE 9-MM
FRICTION CHART FOR AIR
Reprinted with permission from ASHRAf Guide And Data Book